The present inventive concept herein relates to X-ray tubes, and more particularly, to an X-ray tube that can minimize an X-ray focal spot size and a method of controlling an X-ray focal spot using the same.
An X-ray tube using a cold cathode electron source as an emitter generates electrons from the emitter by a mesh type gate electrode disposed in a vacuum container and accelerates the generated electrons by several to several hundreds of kilovolts to make the accelerated electrons strike a target anode electrode. As a result, an X-ray is generated. The generated X-ray includes a characteristic X-ray determined by a unique characteristic of material used in the target anode electrode and a continuous X-ray generated by deceleration of the accelerated electrons. At this time, at least one focusing electrode is selectively added between the anode electrode and a gate electrode to make an electron beam focus on one point of the anode electrode.